Transcriptional regulators in eukaryotic cells are organized into families of genes characterized by their DNA-binding domain and DNA sequence specificity (homeo domain, b-ZIP, HLH, ets domain, Rel homology region, etc.) (see, e.g., Pabo, et al., Annu. Rev. Biochem., 61:1015-1023 (1992)). Although some functional redundancy exists, the specific function of each member of a given family is defined by a configuration of factors involving tissue-specificity and cell cycle regulation, response to extracellular signals, level of expression, interacting proteins, target specificity, kinetics of interaction and effect on transcription (positive or negative). However, the members of a family are usually involved in a common function (e.g., homeo genes and development, AP1 genes and mitogenic stimulation, etc.). The ets family of genes recognize a common target sequence and have been implicated in cellular proliferation and tumorigenesis (see, e.g., Seth, et al., Cell Growth Differ, 3:327-334 (1992); Macleod, et al., TIBS, 17:251-256 (1992); Wasylyk, et al., Eur. J. Biochem., 211:8-19 (1993); and Janknecht, et al., Biochim. Biophys. Acta, 1155:346-356 (1993)). Several growth-related genes contain a functional ets-binding site (EBS) in their regulatory region, including c-fos (for review see Treisman, et al., Curr. Opinion Genet. Dev., 4:96-101 (1994); Karin, et al., Curr. Opinion Cell Biol., 6:415-424 (1994)), Jun-B (Coffer, et al., Oncogene, 9:911-921 (1994)), Rb (Savoysky, et al., Oncogene, 9:1839-1846 (1994)), c-MYC (Roussel, et al., Oncogene, 9:405-415 (1994)) and ETS2 (Mavrothalassitis, et al., Cell Growth Differ, 2:215-224 (1991)), indicating that members of the ets family may play a key role during mitogenic stimulation by regulating the transcription of these genes. Furthermore, recent reports indicate that the activity of some ets family members can be regulated by the ras/MAPK pathway (Janknecht, et al., EMBO, 12:5097-5104 (1993); Rao, et al., Oncogene, 9:1855-1860 (1994); O'Neill, et al., Cell, 78:137-147 (1994); Brunner, et al., Nature, 370:386-389 (1994) and, thus, provide a possible mechanism for the coordinated regulation of the function of some ets genes during mitogenic stimulation.
In an efforts to analyze regulation of the ETS2 gene, its promoter was isolated and characterized (Mavrothalassitis, et al., Oncogene, 5:1337-1342 (1990), Mavrothalassitis, et al., Proc. Natl. Sci. USA, 87:1047-1051 (1990)), and sites where protein interaction is required for promoter function were identified (Mavrothalassitis, et al., Cell Growth Differ., 2:215-224 (1991)). One of the DNA-protein interaction sites on the ETS2 promoter, designated H1, is an ets-binding site, thus suggesting a regulatory loop among the members of the ets family. However, neither ETS1 nor ETS2 are capable of regulating ETS2 transcription via this site, and they both have a low affinity for this particular sequence, indicating that other members of the family are responsible for the transcriptional regulation of the ETS2 gene.
As such, there remains a need in the art for the identification of the gene responsible for the transcriptional regulation of the ETS2 gene.